Prophylactic Phenobarbital after Resolution of Neonatal Seizures (PRO-PHE-NO) The treatment of infants with antiepileptic medications after the resolution of neonatal seizures is highly variable and controversial. Infants are commonly treated with phenobarbital after their seizures have resolved to prevent recurrence. Data to support this practice are lacking but animal models suggest that the neonatal brain is vulnerable to repeated seizures. Yet exposure of the developing brain to phenobarbital for prolonged periods may have deleterious consequences. We are proposing a multi- center, randomized, clinical trial (RCT) to determine if continued treatment with phenobarbital reduces seizure recurrence without adversely affecting neurodevelopmental outcome or if infants'outcomes are improved if no prophylactic medication is given. We will identify infants with seizures beginning in the first week that resolve within 7 days and randomize them to receive phenobarbital or placebo daily for four months. Via visits and frequent telephone contacts over the first six months, we will determine the rate of seizure recurrence. The primary outcome, neurodevelopmental status, will be assessed at 18-22 months using the Bayley Scales of Infant Development. Additional subgroup analyses are planned to determine the contribution of seizure etiology to outcome and predictive value of initial EEG classification. The trial will be conducted at 18 sites, chosen for their experience and proven track record for enrollment and retention in this specific population. The trial will be coordinated by the Clinical Trials Coordination Center at the University of Rochester and overseen by a Steering Committee composed of experienced trialists representing neonatology and pediatric neurology, biostatistics, and clinical trial administration. Extrapolation from the results of an RCT of phenobarbital prophylaxis after febrile seizures in children suggests that phenobarbital may adversely affect brain development and may be ineffective in preventing seizures. Based on this previous RCT that resulted in near universal change in practice (the elimination of prolonged use of phenobarbital after simple febrile seizures), we anticipate that the data we generate may have a similar impact on standard of care for infants with neonatal seizures. PUBLIC HEALTH RELEVANCE: The treatment of infants with medications after their seizures have stopped is very variable. No one knows if continuing treatment with phenobarbital for up to several months is helpful or harmful. This clinical trial is designed to help answer that question and provide data that will help determine standard of care for these children.